The present invention relates to vacuum hold downs and in particular to vacuum cups for CNC machines.
Various machines exist for performing operations on various types of materials. Vacuum is often used to hold the material in place while the operations are performed. Examples of such machines are Biesse machines made for boring and routing of engineered (for example, particle board) and solid wood, composited, plastics, and soft metals (for example, aluminum). These, and other machines, often utilize vacuum pods or cups which may be positioned for a particular work piece or operation. The cups may interface with the machine in various manners, and are generally approximately square and approximately six inches across, although the size and shape may vary.
Known cups are made from a phenolic material. Phenolic material is generally a plastic-like resin which is both hard and strong. Phenolic material is commonly used in as a wood worked surface, for example, as an insert for router tables, because cutters can cut into the phenolic material without damaging the cutter. Vacuum cups generally have narrow edges outlining the perimeter of a top surface of the cups for providing a vacuum seal, and cups made from the phenolic material are easily damaged when a cutter meets the narrow edges or when material is loaded onto the machine. The edges may be cracked, or a portion of the edge may break away. Unfortunately, even a small crack or chip is likely to spoil the cup's ability to maintain vacuum and prevent further use. The Phenolic (or similar hard material) also require a gasket to form a vacuum seal and material may slip on the hard surface. Such gaskets are often expensive and may easily be damaged.